Additional Diagnostic Value of Computed Tomography Perfusion for Detection of Acute Ischemic Stroke in the Posterior Circulation
P osterior circulation stroke accounts for 20% of ischemic strokes. Clinical signs and symptoms of anterior and posterior ischemic stroke may overlap, causing a delay in making the correct diagnosis. 1 In the acute stage, noncontrast computed tomography (NCCT) is used to exclude cerebral hemorrhage and pathologies other than ischemic stroke and to detect early signs of ischemia. CT angiography (CTA) can provide information on the presence and site of an arterial occlusion. CTA source images
... -SI) can also help to detect ischemic changes. 2 CT perfusion (CTP) can detect ischemic perfusion defects, with a pooled analysis sensitivity of 80% (95% confidence interval [CI], 72%-86%) and a specificity of 95% (95% CI, 86%-98%) for early diagnosis of stroke. 3 The additional diagnostic value of CTP compared with NCCT and CTA for posterior circulation stroke has not been analyzed. We investigated the additional diagnostic value of CTP to CTA-SI and NCCT for infarct detection and localization in patients suspected of acute ischemic posterior circulation stroke. Methods Patients All patients participated in the prospective, multicenter, observational Dutch acute stroke study (DUST; ClinicalTrials.gov NCT00880113) in which the diagnostic values of CTA and CTP within 9 hours after onset of the neurological deficit were investigated in patients with acute ischemic stroke. 4 We selected consecutive patients between May 2009 and December 2012 with suspected acute posterior circulation ischemic stroke as defined in the Oxfordshire classification. 5 Reasons for exclusion were poor image quality, not all 3 posterior circulation Alberta Stroke Program Early CT Score (PC-ASPECTS) 6 levels included in the CTP slab or missing follow-up imaging. Background and Purpose-Detection of acute infarction in the posterior circulation is challenging. We aimed to determine the additional value of tomograpy (CT) perfusion to noncontrast CT and CT angiography source images for infarct detection and localization in patients suspected of acute ischemic posterior circulation stroke. Methods-Patients with suspected acute ischemic posterior circulation stroke were selected from the Dutch acute Stroke Trial (DUST) study. Patients underwent noncontrast CT, CT angiography, and CT perfusion within 9 hours after stroke onset and CT or MRI on follow-up. Images were evaluated for signs and location of ischemia. Discrimination of 3 hierarchical logistic regression models (noncontrast CT [A], added CT angiography source images [B], and CT perfusion [C]) was compared with C-statistics. Results-Of 88 patients, 76 (86%) had a clinical diagnosis of ischemic stroke on discharge and 42 patients (48%) showed a posterior circulation infarct on follow-up imaging. Model C (area under the curve from the receiver operating characteristic curve=0.86; 95% confidence interval, 0.77-0.94) predicted an infarct in the posterior circulation territory better than models A (area under the curve from the receiver operating characteristic curve=0.64; 95% confidence interval, 0.53-0.76; P C versus A <0.001) and B (area under the curve from the receiver operating characteristic curve=0.68; 95% confidence interval, 0.56-0.79; P C versus B <0.001). Conclusions-CT perfusion has significant additional diagnostic values to noncontrast CT and CT angiography source images for detecting ischemic changes in patients suspected of acute posterior circulation stroke. (Stroke. 2015;46:00-00.